So it's been 5 episodes since the apparent new Black Canary has been introduced and while she does appear to be a good person there are a few things I have noted which might indicated otherwise.
First suspicion is her name Dinah Drake, now this has been bugging me since day one. We originally thought her name was Tina Boland which even Captain Singh confirmed and we saw Curtis bring up her official C.C.P.D. profile, even her boyfriend Vince thought this was her name. Then she drops the bombshell that her real name is Dinah which again also just so happens to be Laurel’s first name, just as Oliver is trying to find a successor to Laurel’s mantle. Also Dinah Drake is traditionally the mother of Dinah Laurel Lance who in the series just so happens to have a mother named Dinah. What if Dinah’s name really is Tina Boland and she’s using the name Dinah Drake to gain Oliver’s trust because it just so happens to be the name of his ex-girlfriend, who is the reason he even sought out Dinah/Tina in the first place, because she is working with Prometheus. While legally changing one’s name for witness protection isn’t unheard of in real life these shows do have a habit of misleading us with fake names for villains, especially if it's Golden Age heroes they are pretending to be.
After all look at Zoom and Prometheus. Both introduced themselves as “Jay Garrick” and “Adrian Chase” the names of two very old superheroes known as “The Flash” and “Vigilante”. However later they were both exposed as Hunter Zolomon and Simon Morrison while their fake names were the real names of other individuals, and I’m guessing that Vigilante in the series is the real Adrian Chase. Even if Dinah Drake really is her name it wouldn’t be the first time they’ve taken a hero character and turned her into a villain with they did with Artemis. Also could the fact that she has Earth-2 Laurel’s powers be an indication of her true nature? Earth-1 Laurel had a collar and Earth-2 Laurel has powers so does that mean that Earth-1 Dinah is Black Siren while Earth-2 Dinah is Black Canary? Just a random thought, but I've always found that to be just a bit too convinent even by this show's standards that Dinah has those powers. As Ragman spells out it could be fate and while that could be true, fate can either have good results or bad.
Prometheus is also still too well informed of events before they happen which we’ve seen is because he was working with Artemis, but now with her cover blown and even if he is working closely with Oliver at the mayor’s office there is only so much Adrian/Simon can know. But if Dinah/Tina is working with him then he still has an inside person in Team Arrow, and he does seem convinced he's 10 steps ahead and even told Oliver he's done everything he's wanted so far. Also the scene between Dinah and Adrian in 5x15 made me a bit suspicious because he took the piece of Vigilante’s visor from Dinah, promising to return it for her, but was acting very werid around her. Then he returned to the police station with Captain Pike but he left the visor piece but it looked as though Dinah was waiting for Adrian to carry out that exact move.
Also, and I have made this point in several posts but since it’s relevant to this one and for those who haven’t read my previous posts I will write it again, I think Dinah’s presence in Star City is because of Prometheus. Oliver promised Laurel he’d find a successor to the Black Canary mantle but he hadn’t done this until Prometheus sent Earth-2 Laurel after him, then encountering her motivated Oliver into keeping his promise to Earth-1 Laurel hence how he met Dinah Drake. I think Prometheus used Earth-2 Laurel because he knew this would motivate him into keeping his promise to Earth-1 Laurel. I originally thought that maybe Prometheus simply wanted Oliver to find a Black Canary successor and cared little for who, and finding a meta-human with Earth-2 Laurel's powers as just by luck. However I'm wondering if Prometheus actually did intend for Oliver to find Dinah herself. Wouldn’t this just be the most awful way to torment Oliver believing he’s finally honoured Laurel’s memory only to have disgraced it? It would also explain what Prometheus intent with Black Siren was which I never really understood it because simply tormenting Oliver seems a bit low-key for someone who just manipulated Oliver into killing an innocent man, turned one of his own team against him and murdered people to form anagrams for the List.
I don’t really have too much to go on but I don’t trust Dinah Drake because I think there is something deeper to her character that they aren’t telling us yet.